1. Field of the Invention
This invention pertains to the field of laminates having an improved pressure sensitive adhesive layer. More particularly, this invention relates to the method of making improved pressure sensitive adhesive coated laminates for covering substrates for decorative and/or protective purposes or for adhesive tapes, labels, and the like.
2. Description of the Prior Art
The development of pressure sensitive adhesive systems has resulted in their use in a great variety of areas, such as, for tapes, decals, decorative and protective coverings in sheet form for walls, furniture, and the like, self-stick floor coverings, and generally, for any purpose wherein it is desired to adhere an article to a substrate.
Because of the increased movement towards the so-called "do-it-yourself" type of home improvements and decorating, many articles, such as, wall coverings, counter coverings, tile appliques, shelving covers and edgings, and the like, are now sold with pressure sensitive adhesive coatings thereon. Such pressure sensitive adhesive coatings facilitate the application of such articles to the desired substrate by eliminating the need to apply a separate adhesive or to utilize another type of securing device, such as nails, screws, staples, etc.
One of the problems with such pressure sensitive adhesive coated articles is that, in use, they are extremely difficult to position and, if necessary, reposition, even immediately after the application to the substrate. This problem is particularly severe with articles which are in the form of decorative and protective sheets coated with a pressure sensitive adhesive, and which are used to cover substrates, e.g., walls, cabinet tops, furniture, etc. Very often, such sheets or laminates possess decorative patterns on the outer face and it is important that the proper matching of the patterns from adjacent sheets be obtained. Moreover, it is often important that the seams between adjacent sheets be straight, uniform, and parallel.
Another problem which arises, particularly with larger pieces or sheets, such as, when one is attempting to cover a large piece of furniture or large wall area, is the difficulty in handling the sheet and the avoidance of touching of one area of the pressure sensitive adhesive coated side of the sheet with another area of the same side. When this occurs, the sheet will fold and the respective touching areas must be pulled apart. This can become extremely cumbersome, particularly with large sheets.
It also can result in removal of areas of the pressure sensitive adhesive coating when an attempt is made to pull the touching areas apart and cause discontinuities of the pressure sensitive adhesive coating as well as produce torn, stretched or wrinkled areas in the facing sheet which is usually made from paper or plastic sheeting or film.
Additionally, on application of the laminate to a substrate, folds, wrinkles, and bubbles often appear. These are relatively difficult to remove because of the aggressiveness of the pressure sensitive coated sheet for the substrate. This can be particularly troublesome when the facing layer is relatively thin, such as, for example, a thin film of vinyl.
U.K. Patent Specification No. 1,541,311 published Feb. 28, 1979 discloses a method of making a pressure sensitive adhesive coated laminate which overcomes many of the difficulties referred to above. The improvement therein disclosed involves the application between the pressure sensitive adhesive layer and the release surface of a means for decreasing the zero-minute peel value of the facing layer-pressure sensitive adhesive layer of the laminate. This means comprises a uniform and discontinuous layer of a coatable polysiloxane and, it is disclosed in said patent, that the presence of such means at the surface of the pressure sensitive adhesive yields a product which overcomes many of the disadvantages and handling difficulties present in products of this type previously available.
U.S. Pat. No. 4,151,319 granted Apr. 24, 1979, also discloses a method of making a pressure sensitive adhesive coated laminate which overcomes many of the difficulties referred to above. The improvement therein disclosed involves the application of a modified pressure sensitive adhesive layer containing a means for decreasing the zero-minute peel value of the facing layer-pressure sensitive adhesive layer of the laminate. This means comprises a material which produces a low zero-minute peel value intimately mixed in the pressure sensitive adhesive, e.g., a polysiloxane and, it is disclosed in said patent, that the presence of such means in the pressure sensitive adhesive yields a product which overcomes many of the disadvantages and handling difficulties present in products of this type previously available. Although the polysiloxanes used are eminently suitable, some of the newer more recently developed pressure sensitive adhesives, especially the water-based compositions, will be more advantageously used if improved means, especially siloxane compositions are provided, to secure such advantages, among others, such as lower face to face adhesion, better lubricity, and superior adhesion properties. Such improved pressure sensitive adhesive compositions and their use in preparing superior repositionable laminates are the subject matter of the present invention.